Answer:
Investment in fund b = $15,000
Explanation:
Let us assume funds invested in fund b = x while the sum total of funds invested in fund a & b = Y .ie Y = $6000 + x
Fund A returned $6000 * 3/100 = $180
Fund B returned = x & 10/100 = x/10
8%y(total returns) = funds a returns + fund b returns
8%y = $180 + (x/10)
let is replace y with 6000 + x
(6000 +x) * 8% = 180 + (x/10)
480+ 8x/100 = 180 + (x/10)
480 - 180 = (x/10) - (8x/100)
300 = (10x - 8x )/100
300 = 2x/100
300*100 = 2x
30,000 = 2x
x = 15, 000